Cooling brakes with water as a normal procedure
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Hi Rubber Dog,
No, not really.
The energy released by burning Hydrogen in the Oxygen released will exactly balance the energy absorbed during the splitting.
Hence no exothermic reaction.
A dangerous situation.
The energy released by burning Hydrogen in the Oxygen released will exactly balance the energy absorbed during the splitting.
Hence no exothermic reaction.
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It is a bad practice but I have in the past grabbed a case of liter bottles to make an on time turn happen, was always careful to slowly douche the shroud only (never direct contact with the brake). It works, this was ACMI ops, many years ago. The other option is to take off and leave the gear extended until the temps turn green. I only convinced a crew to do this once, back when the day of common sense was actually an option.
Common sense of just ignorant dumb???
I'd say the latter!! ( for the Airbus anyway )
Yes go on, let's put hot brakes into a wheel well without a Fire detection system and pray it's all good!!
Or let's leave the gear down after T/O to cool those hot brakes ( Against Airbus and Boeing normal SOP's ) all good stuff until the Engine fails at V2 and you need to retract hot gear because you didn't do the takeoff data based on gear down.....
Which you can't anyway unless using Brakes deactivated data.
Airbus put 300c in their limitations for a reason.
Plan ahead your brake cooling requirements ( use reverse, use brake fans etc ) in your transits and follow Airbus SOP's and Limitations
I'd say the latter!! ( for the Airbus anyway )
Yes go on, let's put hot brakes into a wheel well without a Fire detection system and pray it's all good!!
Or let's leave the gear down after T/O to cool those hot brakes ( Against Airbus and Boeing normal SOP's ) all good stuff until the Engine fails at V2 and you need to retract hot gear because you didn't do the takeoff data based on gear down.....
Which you can't anyway unless using Brakes deactivated data.
Airbus put 300c in their limitations for a reason.
Plan ahead your brake cooling requirements ( use reverse, use brake fans etc ) in your transits and follow Airbus SOP's and Limitations
Last edited by nitpicker330; 20th Oct 2013 at 07:01.
Airbus FCOM quote
BRAKE TEMPERATURE
The FCOM limits brake temperature to 300 °C before takeoff is started. This limit ensures that, in the case of hydraulic fluid leakage, any hydraulic fluid, that may come into contact with the brake units, will not be ignited in the wheelwell. This limit does not ensure that, in the case of a high energy rejected takeoff, the maximum brake energy limitation will be respected. Thermal oxidation increases at high temperatures. Therefore, if the brakes absorb too much heat, carbon oxidation will increase. This is the reason why the brakes should not be used repeatedly at temperatures above 500 °C during normal operation. In addition, after heavy braking, the use of brake fans can increase oxidation of the brake surface hot spots, if the brakes are not thermally equalized
BRAKE TEMPERATURE
The FCOM limits brake temperature to 300 °C before takeoff is started. This limit ensures that, in the case of hydraulic fluid leakage, any hydraulic fluid, that may come into contact with the brake units, will not be ignited in the wheelwell. This limit does not ensure that, in the case of a high energy rejected takeoff, the maximum brake energy limitation will be respected. Thermal oxidation increases at high temperatures. Therefore, if the brakes absorb too much heat, carbon oxidation will increase. This is the reason why the brakes should not be used repeatedly at temperatures above 500 °C during normal operation. In addition, after heavy braking, the use of brake fans can increase oxidation of the brake surface hot spots, if the brakes are not thermally equalized
Last edited by nitpicker330; 20th Oct 2013 at 07:23.
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Hi nitpicker330,
For aircraft without brake cooling fans nor brake temperature gauges, but with wheel well Fire Detectors fitted, leaving the gear down after take off was an approved method of cooling the brakes (e.g. B707).
That's probably because they have (a) brake temp gauges and (b) cooling fans fitted to help (a) raise awareness and (b) reduce minimum turn round times.
Common sense of just ignorant dumb???
I'd say the latter!! ( for the Airbus anyway )
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Or let's leave the gear down after T/O to cool those hot brakes ( Against Airbus and Boeing normal SOP's ) all good stuff until the Engine fails at V2 and you need to retract hot gear because you didn't do the takeoff data based on gear down.....
Which you can't anyway unless using Brakes deactivated data.
Which you can't anyway unless using Brakes deactivated data.
The other option is to take off and leave the gear extended until the temps turn green. I only convinced a crew to do this once, back when the day of common sense was actually an option.
I'm on your side.
300c Max for RTO and Fire avoidance
Although having said that the Airbus FCTM does say that "the limit does not ensure that, in the case of a high energy rejected takeoff, the maximum brake energy limitation will be respected"
As per my post above.
300c Max for RTO and Fire avoidance
Although having said that the Airbus FCTM does say that "the limit does not ensure that, in the case of a high energy rejected takeoff, the maximum brake energy limitation will be respected"
As per my post above.
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Don't you suppose that if a water douche was an appropriate method of cooling brakes the manufacturers would have fitted such a system or recommended its use? Dumping cold water onto hot metal is a great way to cause unnecessary and often harmful stress and crystalline changes in the metal and as many car drivers know dunking red hot disks in water is likely to result in said disks warping. Rotating the disks as you drench them is unlikely to make the situation much more acceptable outside a lab or manufacturing process where it is properly planned and controlled.
This daft idea has no place in aviation.
This daft idea has no place in aviation.
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I'm with grounded on this.
In 1st generation turbojet powered aircraft, you did not know how hot your tyres and therefore brakes to a certain extent, would be after a long taxi to t/o in high ambient temperatures at MTOW. If there was any doubt we used to leave the gear down, sometimes for up to 20 mins. Terrain permitting in a lot of cases of course. 250 kts of rushing air is as good as any fan that I know of. Yes we had wheel well fire detectors, but they don't detect a burning bogie being retracted into a wheel well.
Yes you could say it was guesswork but common sense did prevail in most cases.
In 1st generation turbojet powered aircraft, you did not know how hot your tyres and therefore brakes to a certain extent, would be after a long taxi to t/o in high ambient temperatures at MTOW. If there was any doubt we used to leave the gear down, sometimes for up to 20 mins. Terrain permitting in a lot of cases of course. 250 kts of rushing air is as good as any fan that I know of. Yes we had wheel well fire detectors, but they don't detect a burning bogie being retracted into a wheel well.
Yes you could say it was guesswork but common sense did prevail in most cases.
If your wheel well fire detectors didn't detect a fire in a bogie after the wheels retract and the doors closed then I'd get them checked!!
Anyway that was history.
This is 2013.
Anyway that was history.
This is 2013.
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Kynteafrocunta. I am with you on this one. Wanted to say the same thing.
I had a wheel fire on an A300 one day during take off. Locked brake. Tower informed me during TO. Took off, left the gear down, circuit at CDG and overweight landing. Besides the 4 wheels and a brake, they had to change the whole boogey.
I had a wheel fire on an A300 one day during take off. Locked brake. Tower informed me during TO. Took off, left the gear down, circuit at CDG and overweight landing. Besides the 4 wheels and a brake, they had to change the whole boogey.
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Nitpicker330.
"If your wheel well fire detectors didn't detect a fire in a bogie after the wheels retract and the doors closed then I'd get them checked!!"
You said that, not me.
This is indeed 2013. Very observant of you.
Concorde PCG was at the turn of this century.
The DC 8 crash at Jeddah, KSA, early 1990's
The 2 accidents above were caused by tyres, hot or disintegrating. Would suggest you take a read of the report, on the DC8. It should be compusery reading for all aircrew. Wheels and tyres and their condition are capable of killing everyone on board as CFIT.
You may just learn something by studying a bit of history as regards to aircraft accidents. History does have a history of repeating itself.
Did they teach you anything about wheels and tyres on your 330 conversion? No I bet they didn't. The latest AB is uncrash-able I believe.
"If your wheel well fire detectors didn't detect a fire in a bogie after the wheels retract and the doors closed then I'd get them checked!!"
You said that, not me.
This is indeed 2013. Very observant of you.
Concorde PCG was at the turn of this century.
The DC 8 crash at Jeddah, KSA, early 1990's
The 2 accidents above were caused by tyres, hot or disintegrating. Would suggest you take a read of the report, on the DC8. It should be compusery reading for all aircrew. Wheels and tyres and their condition are capable of killing everyone on board as CFIT.
You may just learn something by studying a bit of history as regards to aircraft accidents. History does have a history of repeating itself.
Did they teach you anything about wheels and tyres on your 330 conversion? No I bet they didn't. The latest AB is uncrash-able I believe.
I've been told by the airport fire crews that pouring water onto hot brakes could make them explode because of thermal shock.
I will take their word for it. I certainly wouldn't want to be standing anywhere near a hot brake that was being doused.
I will take their word for it. I certainly wouldn't want to be standing anywhere near a hot brake that was being doused.
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The best I have seen was at the old Bangkok airport -Don Maung - where individual fans driven by small Honda motors could be positioned at each wheel to suck air through the brake units - very effective.
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+1 on fans, not water. Boeing's 747-100SR (short range), which JAL used domestically had, air ducts to the brakes for "quick turns".
If a fairly short leg was flown after a turn was done (and knowing brake temps were good for takeoff), we would lower the gear early for the landing instead of leaving gear down after takeoff. You could watch the temps go down well into the green for the upcoming landing, precluding cumulative brake temp increase during the landing rollout and taxi in, even when near max landing weight.
If a fairly short leg was flown after a turn was done (and knowing brake temps were good for takeoff), we would lower the gear early for the landing instead of leaving gear down after takeoff. You could watch the temps go down well into the green for the upcoming landing, precluding cumulative brake temp increase during the landing rollout and taxi in, even when near max landing weight.
Many years ago I was on a 767 flight test where they were doing max performance brake testing. We'd touch down (hard) and they'd apply max braking (no reverse thrust allowed). It was pretty amazing how fast such a big airplane could stop. We wouldn't be stationary long - less than a minute - and immediately takeoff again using the remaining runway (Moses Lake has a long runway - although in retrospect, between the already hot brakes and the remaining runway, it could have been interesting if we'd needed to RTO 
).
After takeoff, they'd leave the gear down to cool the brakes. After maybe 15 minutes they'd get word from instrumentation that the brakes were cool enough and we'd do it again. We did several hours of flight testing without ever retracting the gear - even leaving them down on the return to Boeing Field when we were done.
).After takeoff, they'd leave the gear down to cool the brakes. After maybe 15 minutes they'd get word from instrumentation that the brakes were cool enough and we'd do it again. We did several hours of flight testing without ever retracting the gear - even leaving them down on the return to Boeing Field when we were done.
Don_Apron
I think you misunderstand what I've been badly trying to say!!
All I've said is
1/ In an Airbus with no wheel well fire detection system don't takeoff with temps above 300c,
2/ Don't leave the gear down after takeoff to cool the brakes ( you shouldn't have taken off in the first place ) in a NORMAL situation without first using appropriate performance adjustments to your data ( if you can )
All of those accidents you mention above are out of the blue emergency situations completely different to what I've been talking about in normal line ops following Airbus limitations and SOP's.
You mentioned you had a wheel well fire detection system that wouldn't detect a burning bogie after gear retraction. All I'm saying is that you should get it checked because that is exactly what it's designed to monitor...if not fire/heat then what are the dual fire detector loops designed to detect in the wheel well? You mean Boeing didn't design it to detect any kind of fire inside the bay????
If the Tower report a brake fire after takeoff on my A330 of course I'm going to leave the gear down as an emergency situation now exists. I would select TOGA to ensure terrain clearance etc and later land ASAP...
That situation is different to deliberately departing with hot brakes.
Don't take out of context what I've said ok...
I think you misunderstand what I've been badly trying to say!!
All I've said is
1/ In an Airbus with no wheel well fire detection system don't takeoff with temps above 300c,
2/ Don't leave the gear down after takeoff to cool the brakes ( you shouldn't have taken off in the first place ) in a NORMAL situation without first using appropriate performance adjustments to your data ( if you can )
All of those accidents you mention above are out of the blue emergency situations completely different to what I've been talking about in normal line ops following Airbus limitations and SOP's.
You mentioned you had a wheel well fire detection system that wouldn't detect a burning bogie after gear retraction. All I'm saying is that you should get it checked because that is exactly what it's designed to monitor...if not fire/heat then what are the dual fire detector loops designed to detect in the wheel well? You mean Boeing didn't design it to detect any kind of fire inside the bay????
If the Tower report a brake fire after takeoff on my A330 of course I'm going to leave the gear down as an emergency situation now exists. I would select TOGA to ensure terrain clearance etc and later land ASAP...
That situation is different to deliberately departing with hot brakes.
Don't take out of context what I've said ok...
Last edited by nitpicker330; 21st Oct 2013 at 00:09.
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Children of magenta
Please read my response before posting a reply. Understand the difference between a brake assy and the shroud that is simply there to dissipate heat. Learn from your piers to understand common practice on the aircraft that operated before your Scarebus ways. I speak of history (lil bit of grey area) AND ALSO PAST COMMON PRACTICE. Eat this up as you wish, I amongst many others are living to tell this story.